1. Field of the Invention
The present invention is in the fields of molecular and cellular biology and biomedical diagnostics and therapeutics. Specifically, the invention relates to novel nucleic acid molecules, proteins and polypeptide fragments encoded thereby, polyclonal and monoclonal antibodies thereto, and methods of using the nucleic acid molecules, proteins/polypeptides and antibodies in diagnostic, prognostic and therapeutic regimens for the control of autoimmune disorders, viral diseases and cancers.
2. Related Art
The nuclear body (NB, also known as nuclear domain 10, PML oncogenic domain, and Kr body) is a nuclear organelle whose function is unknown (Ascoli, C. A., and Maul, G. G., J. Cell. Biol. 112:785-795 (1991); Brasch, K., and Ochs, R. L., Exp. Cell Res. 202:211-223 (1992); Dyck, J. A. et al., Cell 76:333-343 (1994)). Using immunohistochemical staining, NBs appear as 5 to 30 discrete, punctate, dot-like regions within the nucleus. The NB is distinct from other nuclear domains including those involved in DNA replication and mRNA processing. In addition, components of the NB do not co-localize with kinetochores or centromeres (Brasch, K., and Ochs, R. L., Exp. Cell Res. 202:211-223 (1992)). The number of NBs in the cell, and the intensity of antibody staining of these structures, increase in response to stimuli including interferons (IFNs), heat shock and viral infection (Ascoli, C. A., and Maul, G. G., J. Cell. Biol. 112:785-795 (1991)).
The NB is a target of autoantibodies in the serum of patients with the autoimmune disease primary biliary cirrhosis (PBC). Approximately 40% of patients with PBC have antibodies directed against this structure (Evans, J., et al., Arthr. Rheum. 347:31-736 (1991); Szostecki, C. et al., Scand. J. Immunol. 36:555-564 (1992)). Serum from patients with PBC was used to identify and characterize a 100-kDa component of the NB which was designated Sp100 (Speckled, 100 kDa) (Szostecki, C. et al., J. Immunol. 145:4338-4347 (1990)). The fusion of Sp100 to the LexA DNA binding domain has been shown to activate gene transcription in Saccharomyces cerevisiae, and it has been suggested that Sp100 may participate in activation of transcription of specific regions in the genome (Xie, K. et al., Mol. Cell. Biol. 13:6170-6179 (1993)).
A second component of the NB, designated NDP52, was characterized using a murine monoclonal antibody that reacted with the NB (Korioth, F., et al., J. Cell. Biol. 130:1-13 (1995)). A cDNA encoding NDP52 was identified and the predicted amino acid sequence contained coiled coil, leucine zipper and zinc finger motifs. One or more of these domains may be involved in interactions between NDP52 and other components of the NB (Korioth, F., et al., J. Cell. Biol. 130:1-13 (1995)).
A third component of the NB, PML, was identified by several investigators studying the t(15;17) translocation associated with human acute promyelocytic leukemia (APL) (de The, H. et al., Nature (London) 347:558-561 (1990); Borrow, J. et al., Science 249:1577-1580 (1990); Longo, L. et al., J. Exp. Med. 172:1571-1575 (1990); Kakizuka, A. et al., Cell 66:663-674 (1991)). In this translocation, the amino terminal portion of PML is fused to retinoic acid receptor .alpha.(RAR.alpha.). PML was found to co-localize with Sp100 in the NB (Weis, K. et al., Cell 76:345-356 (1994); Koken, M. H. M. et al., EMBO 13:1073-1083 (1994)). Expression of the PML-RAR.alpha. fusion protein in APL cells appears to disrupt the NB; in these cells, the NB antigens are detected in numerous smaller regions in the nucleus described as "microspeckles." Treatment of APL cells with retinoic acid (RA) results in differentiation of myeloid precursor cells and reformation of NBs (Dyck, J. A. et al., Cell 76:333-343 (1994); Weis, K. et al., Cell 76:345-356 (1994); Koken, M. H. M. et al., EMBO 13:1073-1083 (1994)). In patients with APL, treatment with RA results in differentiation of leukemic cells and temporary disease remission (Warrell, R. P. et al., N. Eng. J. Med. 329:177-189 (1993)).
PML, like Sp100 and NDP52, is expressed in a wide variety of human cells and established cell lines. For example, immunoreactive PML is detectable in myeloid precursor cells as well as in erythroblasts and megakaryocytes in the bone marrow (Daniel, M. T. et al., Blood 82:1858-1867 (1993)). In addition, PML has been detected in psoriatic skin lesions, hyperplastic breast and colon tissues, and in the endometrial mucosa during the follicular phase of the menstrual cycle (Koken, M. H. M. et al., Oncogene 10:1315-1324 (1995)). In recent studies, it was demonstrated that PML, like Sp100, is a target of autoantibodies in patients with PBC (Stemsdorf, T. et al., Scand. J. Immunol. 42:257-268 (1995)).
Recently, a lymphoid-restricted homologue of SP100 termed LYSP100 (for "lymphoid-restricted homologue of SP100") was reported (Dent, A. L. et al., Blood 88(4):1423-1436 (1996)). Although found in intact cells as microspeckles associated with the NBs of certain lymphoid cell lines, LYSP100 was reported to be morphologically and spatially distinct from PML in these cells, suggesting that it may represent a novel subnuclear domain. LYSP100 mRNA expression was also found to be restricted to lymphoid tissues such as the spleen, thus further distinguishing this gene from SP100 which is more widespread in its expression (Dent, A. L. et al., Blood 88(4):1423-1436 (1996)).
With the possible exception of LYSP100 (which has not yet been examined), expression of the previously identified components of the NB is enhanced by treatment with IFNs (Korioth, F., et al., J. Cell. Biol. 130:1-13 (1995); Guldner, H. H. et al., J. Immunol. 149:4067-4073 (1992); Doucas, V. et al., Genes & Devel. 10:196-207 (1996)). It has been suggested that IFN induction of increased expression of Sp100 reflects a role for Sp100 in the "anti-viral state" (Guldner, H. H. et al., J. Immunol. 149:4067-4073 (1992)). In support of this notion, it has been demonstrated that IFN-induced expression of PML in Hep2 cells is associated with inhibition of adenovirus replication (Doucas, V. et al., Genes & Devel. 10:196-207 (1996)).
The NB is a site of interaction between viral and host proteins. For example, it has been demonstrated that infection of cells with herpes simplex virus-1 (HSV-1) results in disruption of the NB (Maul, G. G. et al., J. Gen. Virol. 74:2679-2690 (1993); Maul, G. G., and Everett, R. D., J. Gen. Virol. 75:1223-1233 (1994)). Using HSV-1 deletion mutants, disruption of the nuclear body was shown to be a result of the action of the viral protein ICP0. Recent studies have demonstrated that other viral proteins, including the adenovirus E4-ORF3 protein, also interact with this nuclear organelle (Doucas, V. et al., Genes & Devel. 10:196-207 (1996); Puvion-Dutilleul, F. et al., Exp. Cell. Res. 218:9-16 (1995); Carvalho, T. et al., J. Cell. Biol. 131:45-56 (1995)).